Abs, forearms and calves can be worked out pretty strenuously every second day. You should try this rather than doing abs every day. High reps can be good for abs, boxing wise, since they are active for the duration you are in the ring and therefore need endurance. Low reps with weights will build your abs but the endurance will be missing. I find sets of 100 crunches, twists, side bends etc. with a few sets of incline sit ups for 20-30 reps works well for me. Don't forget to train the rest of your trunk, especially your lower back.
